// if the random number is even (condition below is false), the do-while-loop execution ends // if it's uneven (condition below is true), the loop continues by generating a new random number} while (($random % 2) == 1);

// even random number is written to array and for-loop continues iteration until original condition is met$numbers[] = $random; }

There is one major difference you should be aware of when using the do--while loop vs. using a simple while loop: And that is when the check condition is made.

In a do--while loop, the test condition evaluation is at the end of the loop. This means that the code inside of the loop will iterate once through before the condition is ever evaluated. This is ideal for tasks that need to execute once before a test is made to continue, such as test that is dependant upon the results of the loop.

Conversely, a plain while loop evaluates the test condition at the begining of the loop before any execution in the loop block is ever made. If for some reason your test condition evaluates to false at the very start of the loop, none of the code inside your loop will be executed.

If you put multiple conditions in the while check, a do-while loop checks these conditions in order and runs again once it encounters a condition that returns true. This can be helpful to know when troubleshooting why a do-while loop isn't finishing. An (illustrative-only) example:

The last example on this page is simply abuse of the `break` keyword. Also, the suggestion to use `goto` if you don't understand the abuse of `break` is unsettling. (See the manual page for `goto` for more than enough reasons not to use it.)

The final example is generally better expressed using a typical if-else statement.

<?phpif ($i < 5) { echo "i is not big enough";} else {$i *= $factor;

if ($i >= $minimum_limit) { echo "i is ok";

/* process i */}}?>

This version is easier to read and understand. And arguments for code golf are invalid as well as this version is 3 lines shorter.

In conclusion, although you can certainly write code that abuses the `break` keyword, you shouldn't in practice. Keep the code easy to read and understand for whoever inherits your code. And remember, code is for humans not computers.

I'm guilty of writing constructs without curly braces sometimes... writing the do--while seemed a bit odd without the curly braces ({ and }), but just so everyone is aware of how this is written with a do--while...

Also, a practical example of when to use a do--while when a simple while just won't do (lol)... copying multiple 2nd level nodes from one document to another using the DOM XML extension

<?php# open up/create the documents and grab the root element$fileDoc = domxml_open_file('example.xml'); // existing xml we want to copy$fileRoot = $fileDoc->document_element();$newDoc = domxml_new_doc('1.0'); // new document we want to copy to$newRoot = $newDoc->create_element('rootnode');$newRoot = $newDoc->append_child($newRoot); // this is the node we want to copy to

# loop through nodes and clone (using deep)$child = $fileRoot->first_child(); // first_child must be called once and can only be called oncedo $newRoot->append_child($child->clone_node(true)); // do first, so that the result from first_child is appendedwhile ( $child = $child->next_sibling() ); // we have to use next_sibling for everything after first_child?>